Windows makes it easy (although not obvious) to customize the Taskbar with custom icons. You don’t need a third-party app, just the icon files to replace the defaults. If you’re theming your desktop, ...

You can customize your Windows 10 taskbar by centering your icons for an aesthetic look with or without third-party software.

Although Windows 11 shows icons in an Overflow menu on the Taskbar, it is possible to stack or unstack icons on the Taskbar using this tutorial. You can do that with the help of the Registry Editor.